Zürich's new cross-city tunnel, Durchmesserlinie, is to be opened on 15th June. Initially the line will be used only by S-Bahn trains, but once remaining work is completed, long distance trains will start using it from December 2015.

The tunnel essentially peels off the present line west of Oerlikon station to then form an elongated underground S permitting Hauptbahnhof to be approached from the east. The line will have four underground platforms at Hauptbahnhof. Beyond these platform the line will rise to the surface and feed into the station throat. However, a viaduct (presently still under construction) will commence here re-joining the main line at Altstetten. Oerlikon is also being widened from 6 to 8 platforms.